MAX3158EAI+

Overview

The MAX3158EAI+ is a high CMRR RS-485/RS-422 data-communications interface hybrid microcircuit providing ±60V isolation. It operates on a single +5V supply, utilizing external 100V capacitors to transfer power across the isolation barrier. The device contains one transmitter and one receiver, supporting data rates up to 250kbps. It features short-circuit current limiting and thermal shutdown protection. Supply current is typically 25mA when active and drops to 25µA in shutdown mode. The E suffix denotes an extended temperature range of -40°C to +85°C, housed in a 28-pin SSOP package.

Feature Summary

• Provides ±60V isolation for RS-485/RS-422 interfaces using a single +5V logic-side supply.
• Includes fail-safe receiver circuitry guaranteeing a logic-high output when inputs are open or shorted.
• Features pin-selectable half-duplex or full-duplex operation with independent phase control pins.
• Integrates thermal shutdown and driver short-circuit current limiting for overload protection.

Applications

• Industrial controls
• Telecommunications systems
• Local area networks
• Level translation between isolated domains

Procurement Notes

Verify the ordering suffix 'E' confirms the -40°C to +85°C operating temperature range and 'AI' specifies the 28-pin SSOP package. Confirm the '+' suffix indicates lead-free compliance as per standard Maxim Integrated conventions. Ensure the application design accounts for the required external 100V charge-pump capacitors and proper grounding of the ISOCOM pin relative to local ground for stable isolation performance.

Selection Notes

Select this component when galvanic isolation is required between digital logic and field wiring in noisy environments. It serves as a direct replacement for opto-isolated transceivers where lower cost and higher reliability are prioritized. Consider the 250kbps maximum data rate and the specific need for ±60V common-mode rejection capabilities. Verify that the system can accommodate the external capacitor requirements for the internal charge pump.

Part Context

The MAX3158 is part of the Maxim Integrated RS-485/RS-422 transceiver family designed for robust industrial communication. It differs from fully integrated isolated transceivers like the MAX1480 by using discrete capacitors for power transfer rather than an internal transformer. This hybrid approach offers a low-cost alternative to traditional optocoupler-based designs while maintaining high common-mode rejection ratios.

Replacement Considerations

Public confirmed substitute part numbers include MAX3158CAI (commercial grade) and MAX3158EPI (extended grade, PDIP package). Direct functional replacements within the same isolation class may include the MAX1480 family, though these offer fully integrated isolation without external capacitors. Verify pin compatibility and electrical characteristics before substituting.